The Duke and Duchess of Cambridge have used their son's first birthday to issue a heartfelt thanks to everyone who has wished their family well during the past year.

As two touching photographs of William, Kate and Prince George were released to officially mark the toddler's anniversary, the Cambridges paid their own tribute to the public support they have received.

In a short message the Duke and Duchess said: "We would like to take this opportunity on George's first birthday to thank everyone over the last year, wherever we have met them, both at home and overseas, for their warm and generous good wishes to George and our family."

The royal couple and their son have received praise both in the UK and abroad, following the birth of George on July 22 last year.

Well-wishers especially took them to heart when the Cambridges travelled with their son to New Zealand and Australia in April.

William, Kate and George were photographed for the official pictures during a visit to the Sensational Butterflies outdoor exhibition at London's Natural History Museum, of which Kate is a patron.

One image shows George, who will celebrate his first birthday tomorrow, fascinated by a blue morpho butterfly, Morpho peleides, from South America, which has landed on the back of his father's right hand.

The toddler prince, who will one day be king, appears about to pick up the delicate insect as he is sat on a bench with his parents.

In the other picture the Duke and Duchess and their son are transfixed by something above their heads and all three stare at the object, possibly a butterfly.

Sir Michael Dixon, director of the Natural History Museum, said: 'It was a real pleasure to host our patron and her family earlier this month. They seemed to enjoy their visit, wandering through the tropical plants as brightly coloured butterflies took flight around them.

"It was delightful to see Prince George's first experience of the Natural History Museum and I look forward to welcoming them again in the future."

The Cambridges will celebrate their son's first birthday with close family and friends at Kensington Palace and are expected to hold a birthday party.

In the pictures, taken a few weeks ago by Press Association photographer John Stillwell, George is dressed in a pair of dungaree shorts, over a polo-shirt style top and shoes and socks.

The dungarees are from French brand Petit Bateau while mother Kate is wearing a green 1930s-inspired Budding Heart Silk Tea dress by British brand Suzannah, which sells for £475.

The Duchess wore it under a green Erdem coat during her tour of New Zealand in April when she visited the town of Cambridge.

The Prince's blond hair has been swept across his head to create a stylish look and he has what his uncle Prince Harry has described as big chubby cheeks and the appearance of a "young Winston Churchill".

Kate became patron of the museum in April last year. Her first engagement as patron was a gala preview screening of Sir David Attenborough's Natural History Museum Alive 3D in December.